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Conjunctiva
The conjunctiva is a vascularized mucous membrane that covers the anterior surface of the eyeball and posterior surface of the eyelids. It combats infection through its vascular and immunological properties. The conjunctiva has three layers - an epithelial layer, substantia propria layer, and goblet cells that secrete mucus. The sclera is the dense outer coat of the eyeball that protects its contents and maintains the globe's shape. It has three layers - episclera, scleral stroma, and lamina fusca. Both structures are supplied by arteries and veins and contain nerves to detect inflammation or eye movement.
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Conjunctiva
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- 3. Conjunctiva • Introduction • Surfaceanatomy • Conjunctival layers • Blood supply and drainage and nerve supply
- 5. What is conjunctiva? •Vascularized mucous membrane that covers the anterior surface of the globe (bulbar and forniceal conjunctiva) and the posterior surface of the upper and lower eyelids (palpebral conjunctiva).
- 6. Combats infection 1. Highlyvascular 2. The different cell types can initiate and participate in defensive inflammatory reaction 3. Immunocompetent cells that contribute a rich supply of immunoglobulins 4. The surface anatomy (microvilli) and biochemistry (enzymatic activity) enable that tissue to engulf and neutralize foreign particles, such as viruses
- 7. Surface anatomy • Theconjunctiva lines the posterior surface of the upper and lower lids and the anterior surface of the globe • Forms superior fornix(8-10mm from limbus) and inferior fornix(8 mm from limbus) • Caruncle and the plica semilunaris
- 8. Arrow pointing tothe region of the superior fornix Region of the inferior fornix (arrow)
- 9. Medical region ofthe eye showing the caruncle (C) and plica semilunaris (P) Region of the lateral fornix (arrow) 14 mm from the limbus
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- 11. Palpebral conjunctiva • Startsfrom posterior end of the eyelid margin at the mucocutaneous junction • Marked adherent to tarsal plate of lids • Freely movable in fornices (forniceal conjunctiva)
- 12. Follicular reaction •identical tolymphoid follicles •viral and chlamydial infections as well as toxic conjunctivitis due to application of certain topical medications Papillary reaction •chronic inflammatory cells such as lymphocytes and plasma cells •presence of blood vessels at their center •,Allergic conjunctivitis, Bacterial conjunctivitis,Contact lens wears,Superior limbic keratoconjunctivitis.
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- 15. Bulbar conjunctiva • limbusto the forniceal area. • thin and translucent. • loosely adherent to the sclera to allow the eye free movement in all directions. • Approximately 3 mm from the limbus, the bulbar conjunctiva, Tenon's capsule, and sclera become firmly attached, and the conjunctiva cannot be easily picked up. This attachment is routinely encountered during the dissection of a limbal-based conjunctival flap in ocular surgery.
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- 17. Conjunctival layers • Thestratified epithelial layer • The substantia propria layer
- 18. Conjunctival epithelium • 2to 4 layers-upper tarsal portion • 6 to 8 layers-corneoscleral junction, • 8 to 10 layers-conjunctival margins
- 19. Conjunctival epithelium • Columnarin the fornix • Cuboidal on the bulbar and tarsal conjunctiva
- 20. Types of cells •Type I cells are the goblet cells • Type II cells are defined by the numerous 60- to 300-nm electron-dense granules • Type III cells are recognizable by their well developed Golgi complex • type IV cells are characterized by rough endoplasmic reticulum • Type V cells are identified by the high content of mitochondria
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- 22. Goblet cells • middleand superficial layers of the epithelium • 25 by 25 μm • 2.2 μL of mucus daily
- 23. Function of gobletcell mucus • Preserve stability of tear film • Local immunity • Cleansing mechanism of the eye • Traps cell debris, foreign bodies, and bacteria • inflammatory response
- 24. Substantia propria • Connectivetissue layer • Anti-infectious potential • Numerous mast cells (6000/mm3), lymphocytes, plasma cells, and neutrophils are normally present in this layer.
- 25. Substantia propria Superficial lymphoidlayer •Not present at birth •Lymphocytes aggregrated into nodules Deeper fibrous layer •thick, collagenous, elastic tissue and contains the vessels and nerves of the conjunctiva in addition to Krause's glands Senile elastotic degeneration
- 26. Blood supply Internal carotidartery ophthalmic artery The palpebral branches of the nasal and lacrimal arteries of the lid Anterior ciliary artery.
- 27. Venous drainage • numerousthan the arteries • tarsal conjunctiva and the bulbar conjunctiva is directed to the palpebral veins • superior and inferior ophthalmic veins
- 28. Lymphatic drainage • asuperficial plexus and a deeper plexus • Ultimately as in the lids drains to the pre auricular and sub-mandibular lymph glands.
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- 30. Caruncle • small, flesh-likebody that lies to the medial side of the plica semilunaris • stratified squamous epithelium similar to skin, but does not undergo keratinization • Hair,sebaceous and sweat glands, goblet cells and accessory lacrimal glands similar to Krause's glands. • Blood supply-superior palpebral arteries • Nerve supply-infratrochlear nerve • Lymphatic drainage-sub maxillary lymph nodes
- 31. Plica semilunaris • Foldof conjunctiva lying lateral to the caruncle • cul-de-sac of approximately 2 mm in depth is formed when the globe is adducted • nonexistent when the globe is abducted • nictitating membrane in lower vertebrates
- 32. Sclera • Introduction • Development •Gross anatomy • Layers • Blood supply,drainage and nerve supply
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- 34. Introduction • dense connectivetissue that accounts for five sixths of the outer coat of the eyeball • sklera mannix- hard membrane 1.protects intraocular components from trauma, light, and mechanical displacement 2.withstands the considerable expansive force generated by the intraocular pressure maintaining the shape of the globe 3.provides attachment sites for the extraocular muscles.
- 35. Prenatal development • neuralcrest-mesodermal origin • anterior to posterior and from inside to outside 5th week double-layered optic cup or neuroectoderm 6th week Differentiation into sclera and choroid anterior to equator 8th week Backward to the equator 12th week Posterior pole 4th month Scleral spur 5th month Lamina cibrosa
- 36. Postnatal development andage related characterstics • Postnatal- relatively thin, bluish, distensible, small, and translucent • Childhood and puberty-thicker, whiter, less distensible, larger, and more opaque • Adult- poorly distensible,opaque or translucent depending on water content • Elderly- less distensible,yellowish color and senile scleral plaques.
- 37. Gross anatomy five sixthsof the eyeball with a radius of curvature of 12 mm
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- 39. Clinical applications • Thetraumatic scleral rupture • Strabismus surgery.
- 40. Tenons capsule • fascialsheath of the eyeball • extends anteriorly from the limbus backward, envelopes the globe and fuses with the optic nerve dural sheath and with the sclera around the exit of the optic nerve • supports the eyeball within the orbit • permits the eyeball movement produced by the extraocular muscles
- 41. Sclera foramina • anteriorfor the cornea • posterior for the optic nerve
- 42. Anterior scleral foramen •Sclera merges with the cornea at the anterior scleral foramen forming the corneoscleral junction or limbus Fig: longitudinal section through the region of the corneoscleral junction showing the peripheral cornea, the sclera, the conjunctiva, and Tenon's capsule, canal of Schlemm, the trabecular meshwork, and the iris
- 43. Posterior scleral foramen •The exit of the optic nerve • Lamina cribrosa-After piercing the lamina cribrosa, the axons of the optic nerve become myelinated. One of the small perforations is larger than the rest and permits the passage of the central retinal artery and vein.
- 44. Layers of sclera •Episclera • Scleral stroma • Lamina fusca
- 45. Episclera • Superficial aspectof sclera • bundles of collagen circumferentially arranged • rich blood supply anteriorly • thickest anterior to the rectus muscle insertions and becomes progressively thinner toward the back of the eye.
- 46. Scleral stroma • bundlesof collagen intermingled with fibroblasts, melanocytes, elastic fibers, proteoglycans, and glycoproteins • variability in collagen fiber diameter, interlacing in bundles of collagen, and relative deficiency in water-binding substances accounts for the scleral dull- white color.
- 47. Lamina fusca • Browncolor due to melanocytes • grooves for the passage of ciliary vessels and nerves (emissary canals) • attached to the choroid by fine collagen fibers
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- 49. Blood supply • Episclera-anteriorand posterior ciliary arteries • Scleral stroma-relatively avasculature structure
- 51. Venous drainage • Episcleralcollecting veins • Vortex veins Anterior ciliary veins
- 52. Nerve supply • Richin nerve supply • Anterior sclera- long posterior ciliary nerves • Posterior sclera- short posterior ciliary nerves • Pain- inflammation, stretching due to oedema and movement of eye
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- 54. References 1. Fundamentals andprinciples of Ophthalmology,section 2,2014-2015, American Academy of Ophthalmology 2. External Disease and Cornea, Section 8, 2014-2015, American Academy of Ophthalmology 3. Duane's Foundations of Clinical Ophthalmology, Foundation volume 1 4. Jack J Kanski, Brad Bowling, Clinical Ophthalmology, seventh edition 2011 5. M.J. Roper- Hall, Stallard’s Eye Surgery, Seventh Edition, 1989 6. Parsons’ Diseases of the Eye, Twentieth Edition 2007 7. Internet